2002 115 johnson fouled plugs

[sabre11134]

My plugs keep getting fouled after three or four boating trips, Checked compression 120-125 on each cylinder.

 

[ob]

Re: 2002 115 johnson fouled plugs

What type of fouling?Wet,gap bridged,etc.?What plugs are you running?Do you do a lot of slow speed trolling?Also ,list the model number of the engine in question.

 

[sabre11134]

Re: 2002 115 johnson fouled plugs

Plugs are getting wet, plugs are QL78YC some slow speed not a lot Engine M#J115VLSNF This is a bombardier engine.

 

[ob]

Re: 2002 115 johnson fouled plugs

Check to insure that the fuel solenoid primer valve (red lever) is seated all the way closed clockwise in the normal run position.<br /><br />Also post whether the fuel primer bulb will pump up firm and hold before starting engine.This will help eliminate the possibility of a stuck float in one or more carbs.

 

[sabre11134]

Re: 2002 115 johnson fouled plugs

Primer valve in closed position,Primer bulb gets firm

 

[ob]

Re: 2002 115 johnson fouled plugs

Ok,we can rule that out.Only other items that come to mind are weak spark or OMS pump is overoiling.Does the engine perform well at all speeds besides the plug fouling issue?What is the wide open throttle rpm capability as propped?

 

[sabre11134]

Re: 2002 115 johnson fouled plugs

Wide open rpm on a calm day 5200 rpm, boat never went over 5200 rpm from day one Boat does not sound very good at low idle(sound rough),high speed seem to run ok.

 

[ob]

Re: 2002 115 johnson fouled plugs

May have a slow speed needle valve adjustment issue.Also ,you're engine should turn up upwards of 5500-5800 wot.What diameter and pitch prop are you currently running and what length and hull design boat is the 115 pushing?Overpropping will cause the engine to lug and cylinders to load up at any speed.Having the engine mounted too low on transom will have similar effect.Insure that the anti-ventilation plate of the lower unit is roughly even or slightly above the pad of the boat when engine is trimmed down level.

 

[sabre11134]

Re: 2002 115 johnson fouled plugs

I belive i have 13-3/8 x 19 degree sst johnson prop(non stainless).Boat is a 18 foot deep vee hull 20 degree,anti-ventilation plate even with bottom of hull

 

[ob]

Re: 2002 115 johnson fouled plugs

I'd see if your local dealer or prop shop would let you trial run a 17" pitch prop and get the rpms up in the recommended range first before we chase any other problems.However ,as propped,I don't feel would contribute to the low speed idle problem you describe above.That is likely a low speed carburetor issue which needs to be adjusted in gear in water.<br /><br />BTW if your prop is a sst it is stainless.If it'll pull a magnet,that would confirm.

 

[sabre11134]

Re: 2002 115 johnson fouled plugs

Ob Thanks for all your help